1. Field of the Invention
The present invention relates to a thin-film resistor for an attenuator that is utilized in the fourth generation mobile communication, and more specifically, to a thin-film resistor that can be used for an attenuator, in which the thin-film resistor fabricated by a Ti(N) thin-film deposition method has superior electrical characteristics, such as sheet resistance, and superior characteristics in changes of attenuation and voltage standing wave ratio (VSWR) with respect to changes of frequency and L/W.
2. Description of the Related Art
Until present, development and commercialization of parts used for mobile communication (CDMA, PCS, and WLL) and the next generation mobile communication (IMT-2000) are mainly focused on voice and data communication using narrow band frequencies of less than 3 GHz and output power of less than 5 W. Resistive elements used for the voice and data communication are generally thick-film resistors, in which a resistive material is mounted on an Al2O3 substrate in the form of a thick film. Since the resistive elements are fabricated in a small size and have excellent characteristics in narrow band frequencies less than 3 GHz, they are applied to the latest devices such as cellular phones, computers, and the like to implement satisfactory performance. Such resistive elements are fabricated and distributed in the form of a thick film using a thick film technique by KMC Tech. Co. of Korea.
However, it is quite naturally expected that transmission systems of a high power will be constructed for improved mobile communication services that will come within a few years, and thus passive elements for the next generation communication, i.e., high-power passive elements in preparation for the fourth generation mobile communication, are absolutely necessary. For passive elements of the next generation mobile communication, it is desirable to replace thick-film elements with thin-film elements having a higher resistance tolerance, a more precise temperature coefficient of resistance, and superior current-noise and high-frequency characteristics as compared with the thick film element.
Advantages obtained by replacing thick-film resistors with thin-film resistors are as follows: first, decrease of parasite components due to decrease in thickness; second, possibility of implementing Near Zero TCR; third, applicability to monolithic microwave integrated circuit (MMIC) by securing fundamental technologies; and fourth, possibility of constructing mass-production systems. Therefore, in the fourth generation mobile communication using the thin-film elements, it is possible to provide a service capable of processing a large volume of data in a speedy way regardless of time and space using a frequency band of 5.7 GHz. Owing to such advantages, researches on the thin-film resistors are in progress all over the world, and companies such as RD Florida and KDI/Triangle demonstrate data on thin-film resistors using a BeO substrate at a frequency of about 4 GHz. However, since the specification of the thin-film resistors shows a VSWR as high as 1.5, studies for reducing the VSWR are continued.